drop lone "use strict" in function body (#2963)

fixes #2961
2018-02-26 15:22:52 +08:00
parent ba7bad0dbd
commit ace5811691
2 changed files with 39 additions and 0 deletions
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -3024,6 +3024,16 @@ merge(Compressor.prototype, {
        return self;
    });

+    OPT(AST_Lambda, function(self, compressor){
+        tighten_body(self.body, compressor);
+        if (compressor.option("side_effects")
+            && self.body.length == 1
+            && self.body[0] === compressor.has_directive("use strict")) {
+            self.body.length = 0;
+        }
+        return self;
+    });
+
    AST_Scope.DEFMETHOD("drop_unused", function(compressor){
        if (!compressor.option("unused")) return;
        if (compressor.has_directive("use asm")) return;